What is "URI equality" ?

Sections 5.29 and 7.3.4 of the Committee Specification 1 XACMLv3 core
specification define the matching of Category, AttributeId and DataType
XML attributes according to "URI equality". I've always assumed that
URI equality was the same as the matching performed by the
urn:oasis:names:tc:xacml:1.0:function:anyURI-equal function, but I can't
find anything in the specification to justify that assumption since
"URI equality" is not defined anywhere. It would help if the specification
clarified what "URI equality" actually means.

Similarly, there is also a reference to undefined "string equality"
matching in section 5.24.

Regards,
Steven